Brief Report: Bilirubin Formation in the Liver from Nonhemoglobin Sources: Experiments with Isolated, Perfused Rat Liver

Rapid formation of C¹⁴-bilirubin from glycine-2-C¹⁴ or -aminolevulinicacid-4-C¹⁴ has been demonstrated in isolated, perfused rat liver. The kineticsof labeled bilirubin production in vitro were similar to those of the "earlylabeling" pigment fraction observed in intact rats. The magnitude of bilepigment formation from C¹⁴-ALA by isolated liver was comparable to that inintact animals. Derivation of the C¹⁴-bilirubin from hepatic degradation oflabeled hemoglobin was excluded by perfusion of the liver with blood poor inreticulocytes, or with plasma. The findings identify the liver as an importantsource of the "early-labeling" pigment fraction.

Submitted on April 15, 1965 Accepted on June 18, 1965